A sniffer dog runs a nose over suitcases at Incheon International Airport. Koreans who smoke marijuana in Canada, or anywhere else, could face criminal charges at home. Yonhap

By Jung Min-hoThe Korea Customs Service (KCS) has warned Koreans living in Canada not to smoke marijuana as the North American nation moves to allow recreational marijuana sales in just two months.

"It will still be illegal for Koreans to smoke marijuana in Canada or anywhere else," the KCS said Monday. "Koreans who return here after using the drug could face criminal charges."

Canada's Bill C-45, also known as the Cannabis Act, will go into effect on October 17. Canada, the first wealthy nation to legalize marijuana fully, expects the law to keep the drug away from underage users and reduce related crimes.

The KCS said it seized 18 kilograms of marijuana between January and July ― up 365 percent on the same period last year ― after California began sales of recreational marijuana on Jan. 1. The haul is expected to surge once the Canadian law takes effect.

"We will strengthen inspections of people who come from Canada and their belongings as well as all packages from the country," the KCS said. "We will continue our efforts to prevent drug smuggling."